Hi,Lydia
I would like to suggest you to follow these steps to remove the pop ups and then try to install Mcafee anti virus on your computer.
-Download and run Junk ware removal tool and restart the computer-downloads.malwarebytes.org/file/jrt
-Run a malware scan using malware bytes anti malware-https://www.malwarebytes.org/mwb-download/
-Restart the computer
-Reset your browsers For Internet Explorer.
-Open Internet Explorer and click on tools.
-Click on Internet options and click on advanced tab.
-Click on Reset
For Google Chrome first remove the extensions.
-Open Google Chrome
-At the far right, inline with the address bar, click the Menu icon
-Click on settings and at the left side you will see extensions
-Click on extensions and click on delete for all unknown extensions.
-Then click on settings and scroll down to click on show advance settings.
-Scroll down and click on the reset option to reset chrome
For Mozilla Firefox:
-Open Mozilla Firefox
-At the top above the address right click on the grey portion and select menu bar.
-Click on help from and select troubleshoot information.
-Click on refresh Firefox and click on finish
Install ad blocker on all browsers using the link:www.adblockplus.org
-Restart the computer and now Login to your McAfee account to install McAfee anti virus .
Hope these steps will help you to remove the pop ups and in installing McAfee Anti virus on your computer.
Regards,
Kempton